Vitamin D and cancer: maintaining levels key to protection?

Ensuring levels of vitamin D never get low could be a way of
protecting against cancer, suggests a new study from Germany.

Death from fatal cancer was reduced by 55 per cent amongst people
with higher vitamin D levels, according to data collected from
3,299 patients taking part in the Ludwigshafen Risk and
Cardiovascular Health study and reported in the journal Cancer
Epidemiology, Biomarkers & Prevention​.
The study adds to a growing body of science supporting potential
anti-cancer benefits of the vitamin, and increases the volume of
calls for raising the recommended daily allowance from 400 IU to
1,000 IU.
"These data support other studies suggesting that vitamin D
supplementation might be promising for the treatment and/or
prevention of cancer and are in line with the national
recommendation of the Canadian Cancer Society for the
supplementation of 1,000 IU/d vitamin D for all adults during
winter and for persons at high risk for vitamin D deficiency all
year-round,"​ wrote lead author Stefan Pilz from University of
Heidelberg.
The link between vitamin D intake and protection from cancer dates
from the 1940s when Frank Apperly demonstrated a link between
latitude and deaths from cancer, and suggested that sunlight gave
"a relative cancer immunity."
Vitamin D refers to two biologically inactive precursors - D3, also
known as cholecalciferol, and D2, also known as ergocalciferol.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys
to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage'
form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically
active form that is tightly controlled by the body.
Blood levels of 25(OH)D and 1,25-(OH)2D were measured in the study
participants, and over the course of 7.75 years, 95 patients deaths
due to cancer were documented. The most common cancers were lung,
colon, and pancreas.
After adjusting for various potential confounding factors, the
researchers report that people with the highest level of 25(OH)D
(76.3 nanomoles per litre) were 55 per cent less likely to die form
fatal cancer than those with the lowest levels (18.1 nmol/L).
Moreover, every increase of 25 nmol/L in 25(OH)D levels was
associated with a 34 per cent risk reduction, added the
researchers.
However, no association was observed between levels of 1,25(OH)2D
and cancer risk.
"Our finding that 1,25(OH)2D was not associated with increased
risk of fatal cancer does not argue against a crucial role of
1,25(OH)D in the prevention of cancer because intracellular
1,25(OH)2D levels can best be estimated by serum 25(OH)D
concentrations, which are rate limiting for the conversion of
25(OH)D to 1,25(OH)2D,"​ stated the researchers.
The results, while in need of support from additional studies,
indicate a anti-cancer role for maintained vitamin D levels, and
highlight the potential of supplements or fortified foods. This is
particularly important in northern climes were sunshine levels are
not strong enough for long periods for the body to synthesise the
vitamin itself.
Experts call for higher levels ​
Calls to increase the current recommendations of 200 IU per day for
children and adults up to 50 years of age for vitamin D up to 800 -
1000 IU vitamin D3, have become more frequent in both scientific
and public circles.
Vitamin D refers to two biologically inactive precursors - D3, also
known as cholecalciferol, and D2, also known as ergocalciferol. The
vitamin can be manufactured in the body on exposure to sunlight and
also consumed in relatively low quantities from the diet.
However because of the low dietary amounts, and lack of sunshine in
northern climates, with some estimates claiming that as much as 60
per cent of northern populations may be vitamin D deficient.
In adults, vitamin D deficiency may precipitate or exacerbate
osteopenia, osteoporosis, muscle weakness, fractures, common
cancers, autoimmune diseases, infectious diseases and
cardiovascular diseases.
Source: Cancer Epidemiology, Biomarkers &
Prevention​
2008, Volume 17, Number 5, Pages 1228-1233,
doi:1055-9965.EPI-08-0002
"Low Serum Levels of 25-Hydroxyvitamin D Predict Fatal Cancer
in Patients Referred to Coronary Angiography" ​Authors: S.
Pilz, H. Dobnig, B. Winklhofer-Roob, G. Riedmuller, J.E. Fischer,
U. Seelhorst, B. Wellnitz, B.O. Boehm, W. Marz